Determination of Triton X-100 and Its Critical Micelle Concentration by Using Fluorescent Conjugated Polymer

A novel hydrophobic fluorescent conjugated polymer, i e poly[2,5-bisnonyloxy-1, 4-phenylene-ethynylene-9,10-anthrylene] (PPEA) was synthesized by a Sonogashira palladium-catalyzed cross-coupling reaction of 1,4-diethynyl-2,5-bisnonyloxy-benzene and 9,10-dibromoanthracene And their fluorescence behaviors in aqueous solution containing different surfactants were studied The fluorescence of PPEA was dramatically quenched in aqueous solution However, the fluorescence gradually enhanced with the increasing of the concentration of TX-100 Other surfactants such as CTAB, SDS and Tween had little effect on the fluorescence intensity This phenomenon may be ascribed to the fact that PPEA and TX-100 share the same long aliphatic carbon tail The hydrophobic interaction between PPEA and TX-100 might reduce the conformational disorder of PPEA and induce the PPEA chains to become more extended Also, the effects of the amount of THF, the concentration of PPEA, pH, reaction time and coexisted materials on the determination were investigated Under the optimum conditions, the fluorescence intensity was proportional to the concentration of Triton X-100 in the range of 0 similar to 200 and 200 similar to 700 mu mol/L, respectively And the concentration corresponding to the point of intersection of the two calibration graphs was found to be in good agreement with the critical micelle concentration (CMC) of Triton X-100 Therefore, a fluorescence enhancement method based on fluorescent conjugated polymer has been developed It can be used to selectively detect Triton X-100 in the presence of other surfactants and indicate the CMC of Triton X-100 Two synthetic and three real Triton X-100 samples were determined with satisfactory results